1. Technical Field
The present invention relates to a light source device, to a method of manufacturing a light source device, and to a line head module.
2. Related Art
As a printer using an electrophotographic method, a line printer (an image forming apparatus) is known. In this line printer, devices, such as a charger, a printer head (a line head) in the shape of a line, a developing device, a transfer device, and the like are disposed near to a peripheral surface of the photoconductor drum as an object to be exposed. In other words, exposure is performed on the peripheral surface of the photoconductor drum charged by the charger, through selective light-emitting operation of light-emitting elements provided in the line head, thereby forming an electrostatic latent image, and the latent image is then developed with toner supplied from the developing device, so that the resulting toner image is transferred onto a sheet by the transfer device.
This line printer of an electrophotographic type generally employs a method in which beams emitted from line head are caused to pass through a Celfoc (registered trademark) lens array (trade name of Nippon Sheet Glass Co., Ltd.) so that an image is formed and exposed on the photoconductor drum. In this lens array, a larger number of columnar Celfoc (registered trademark) lenses that perform erect unmagnified image formation are arrayed so as to enable a wide range of image formation.
Meanwhile, as the light-emitting elements of the line head, as mentioned above, light-emitting diodes are generally used. However, the light-emitting diodes have a problem in that it is extremely difficult to array several thousands of light-emitting points with high precision. Thus, in recent years, for example, JP-A-10-55890 suggests an image forming apparatus including, as an exposing unit, a light-emitting element array that employs, as the light-emitting elements, organic electroluminescent elements (hereinafter, referred to as organic EL elements) into which the light-emitting points are built with high precision.
However, the organic EL elements which are in practical use at the present moment have a relatively small luminescence intensity. Therefore, it is difficult to obtain a quantity of light required for exposure. In addition, if the current density of the organic EL elements is increased in order to increase the light quantity, the lifespan of the organic EL elements is shortened.